I don't think it is a joke or a scam. The tank costs $32.37 but people can obtain discounts by completing some missions.

Yesterday took me all day to complete the mission but I was goofing around a lot playing the Leo to get the Emil. On the plus side I managed to "accidentally" complete MT-15 for the T55A after more than a year of not really giving it much thought. The MT-15 "mission completed" notification popped up after one of my last battles in the Leo before upgrading to the Emil. Very nice surprise!

The one for today is kind of daunting for me. Ten wins as a top three XP earner can be difficult. That would average out to twenty battles for me just to win, never mind being in the top three. Maybe light tanks doing a ton of spotting and tracking? Churchill III spamming damage at tier 5? Some players know exactly which tanks to use for what missions, I'm just not one of them. I guess I'll find out soon enough if it is a "mission completed" day or a token day, LOL.

For fun I kept track and I have to say it was a much better day than yesterday with a much better win rate than usual for me. I got really lucky. I was thinking at least forty battles but I made it in thirty.